For example, when a process target layer on a wafer is to be processed, the wafer is mounted on an electrostatic chuck (ESC) base through a high voltage (HV) electrode. In some cases, the process target layer, a first hard mask layer, a second hard mask layer and a resist layer are formed on the wafer, an opening that penetrates through the resist layer, the second hard mask layer and the first hard mask layer is formed by dry etching, and a portion of the process target layer within the opening is processed by dry etching.
In these cases, when the second hard mask layer is removed during the processing of the process target layer within the opening, the state of the wafer varies and the potential of the wafer is changed. Therefore, when the potential of the wafer is changed, a dry etching apparatus changes the potential of the ESC base to adjust the potential of the ESC base to be equal to the potential of the wafer. As a result, the potential difference between the wafer or ESC base and the HV electrode is changed, and a current flowing through the HV electrode increases. The increase of this current may adversely affect the dry etching.